1. Field of the Invention
The present invention relates to the field of detecting motion picture film sources in film material.
2. Description of the Related Art
In U.S. Pat. No. 5,734,735, a method and system is described that analyzes a series of video images. The types of production media used to produce these video images are detected. Each of the series of video images is segmented into a series of cells in order to retain spatial information. The spatial information is used to detect the type of production media. No technique is disclosed to detect types of production for different scenes within one image, coming from different sources and being mixed to form the single image.
U.S. Pat. No. 6,014,182 also relates to methods for detecting motion picture film sources. Such a detection might be useful in several environments, e.g., line doublers, television standard converters, television slow motion processing and video compression. For instance, a 60 Hz NTSC television signal has a 24 frame/second motion picture film as its source. In such a scheme, a 3-2 pull-down ratio is used, i.e., three video fields come from one film frame while the next two video fields come from the next film frame, etc. For example, calling subsequent video fields A, B, C, D, E, a 3-2 pull-down ratio would look like AAABBCCCDDEEE. Other sources have a 2-2 pull down ratio or relate to video camera, as is known to persons skilled in the art. Thus, comparing successive fields yields information about the motion picture source used.
U.S. Pat. No. 5,365,280 proposes using different motion vectors for different fields and generating a picture signal processing mode control signal that can be used by a television receiver as an indication that the fields relate either to movie-film or non-movie-film.
Motion estimation algorithms can be found in M. Tekalp, “Digital Video Processing”, Prentice Hall, ISBN 0-13-190075-7. An overview of object-based motion estimation methods is given by Paolo Vicari, “Representation and regularization of motion fields with region-based models”, thesis for the Politecnico di Milano, No. 598034.
So far, the prior has concentrated on detecting motion picture sources of either films having fields originating from a single motion picture source or films having subsequent fields originating from two or more different motion picture sources. However, an increasing number of films comprise mixtures of images within fields that originate from different motion picture sources. None of the prior art methods discussed above, are able to detect the picture repetition mode of individual images within fields of a film. For instance, in applications in picture rate conversion, however, an indication of the origin of the individual images within the fields needs to be known. More particularly, it is necessary to know whether the video originates from film material to optimally perform de-interlacing and film judder removal.